This invention relates to trinary input devices and methods.
In many digital systems, different configurations are required, wherein the particular configuration needs to be sensed by the digital system. If a large number of configurations arc required, a binary encoding may be used where the number of options available is 2.sup.n, wherein N is the number of pins used. As the name suggests, binary systems have only two possible values per pin (usually high and low).
In many cost sensitive applications. where each extra pin may cause a significant extra cost factor (for example encoding serial numbers into car alarm remote commanders), a three level (trinary or tri-state) encoding is used, where each pin has three possible values, namely high, low and mid. The electronic circuitry required to sense trinary levels is more complex than that required to sense binary levels. However, the extra complexity is insignificant when compared to the reduced packaging costs in adopting trinary encoding. Trinary encoding also provides many more options than binary encoding. For example, whereas four binary bits encodes sixteen possible values, four trinary bits encodes 81 possible values.
However, a disadvantage of conventional trinay encoding systems is that the encoding has a base of nine. This causes some difficulties for encoding as users are not used to working to base nine.
Accordingly, the invention seeks to provide an enhanced, or extended trinary encoding, which is more user friendly to use, as well as providing more options.